This invention relates generally to variable differential switching apparatus, and more particularly concerns the use of magnetic means providing different strength field presented to differentially control a field responsive element depending upon the direction of relative motion of the element and the magnetic means.
In the past, switching operations were effected by magnets in generally the same manner whether or not a magnetically responsive element traveled forwardly or reversely. Thus, if the element were displaced or "latched" by the field of magnet A, as the element passed relatively into that field, the element became unlatched when it passed relatively out of that field, and a switch could be controlled in response to such latching and unlatching. The travel of the element between latched and unlatched conditions, and hence the switching function, was limited by the existence of the field of the magnet A, which in turn was a function of the size of the magnet. Also, no way was known to vary the latching and switching apparatus as a function of travel direction, particularly in the simple and effective manner now afforded by the present invention, using permanent magnets of different field strengths.
There is need for apparatus that will provide variable differential latching and switching operation using permanent magnets in the simple, effective and novel manner as now afforded by the present invention.